With Buddha scratched out of Saturday's Kentucky Derby due to injury, trainer Bill Mott moved quickly Friday to secure the services of Hall of Famer Pat Day to ride Blue Burner in the classic.Also, the scratch of Buddha led Churchill officials to alter the gate positions from which the horses from posts 1-9 will start. The program numbers, which coincided with the original post positions, will remain the same. Churchill officials handled the situation by moving each horse from posts 1-9 one position out. So, Johannesburg, who drew the inside 1 post, will now actually break from gate position 2 but will still be the number 1 horse in the program. Wild Horses goes from post 2 to 3; Perfect Drift from 3 to 4; Lusty Latin from 4 to 5; War Emblem from 5 to 6; Ocean Sound from 6 to 7; Request from Parole from 7 to 8; Essence of Dubai from 8 to 9; and Medaglia d'Oro from 9 to 10. The post positions from 11 to 20 remain unchanged.The mount on Blue Burner, the fifth-place finisher in the Wood Memorial who had been installed at 30-1 morning-line odds, became open after jockey Corey Nakatani was injured in a spill Thursday at Hollywood Park."Corey was still experiencing some dizziness and the physician recommended he not ride Saturday because he may have a concussion," Mott said. "With the unfortunate injury to Buddha, Pat became available, and at this point, it would be a no-brainer. Pat and I have won a lot of races here together.""I did not want somebody to get taken off in order to allow me the opportunity to ride," Day said. "If somebody was named on a horse and they were able and willing to ride, I wanted the opportunity to go to them."